This sutra is known for its extensive instruction on the concept and usage of skillful means – (Sanskrit: upaya, Japanese: hoben), the seventh paramita or perfection of a Bodhisattva – mostly in the form of parables. It is also one of the first sutras to use the term Mahayana, or "Great Vehicle", Buddhism. Another concept introduced by the Lotus Sutra is the idea that the Buddha is an eternal entity, who achieved nirvana eons ago, but willingly chose to remain in the cycle of rebirth (samsara) to help teach beings the Dharma time and again. He reveals himself as the "father" of all beings and evinces the loving care of just such a father. Moreover, the sutra indicates that even after the Parinirvana (apparent physical death) of a Buddha, that Buddha continues to be real and to be capable of communicating with the world. The idea that the physical death of a Buddha is the termination of that Buddha is graphically refuted by the movement and meaning of the scripture, in which another Buddha, who passed long before, appears and communicates with Shakyamuni himself. In the vision of the Lotus Sutra, Buddhas are ultimately immortal. A similar doctrine of the eternality of Buddhas is repeatedly expounded in the tathagatagarbha sutras, which share certain family resemblances with the teachings of the Lotus Sutra. In terms of literary style, the Lotus Sutra illustrates a sense of timelessness and the inconceivable, often using large numbers and measurements of time and space. Some of the other Buddhas mentioned in the Lotus Sutra are said to have lifetimes of dozens or hundreds of kalpas, while the number of Bodhisattvas mentioned in the "Earth Bodhisattva" chapter number in the billions, if not more. The Lotus Sutra also often alludes to a special teaching that supersedes everything else that the Buddha has taught, but the Sutra never actually states what that teaching is. This is said to be in keeping with the general Mahayana Buddhist view that the highest teaching cannot be expressed in words. The ultimate teaching of the sutra, however, is implied to the reader that "full Buddhahood" is only arrived at by exposure to the truths expressed implicitly in the Lotus Sutra via its many parables and references to a heretofore less clearly imagined cosmological order. Skillful means of most enlightened Buddhas is itself the highest teaching (the "Lotus Sutra" itself), in conjunction with the sutra's stated tenets that all other teachings are subservient to, propagated by and in the service of this highest truth and teaching aimed at creating "full Buddhas" out of pratyekabuddhas, lesser buddhas and bodhisattvas. The text also implies a parent-child relationship between the innumerable Buddhas and human beings and other types of beings, with an explicit indication that all religions and paths are in some way or another part of the skillful means of this highest teaching, which reaches its fullest expression in the Lotus Sutra. The various religious institutions and their doctrinal proponents notwithstanding, all paths are then, officially speaking, part of the skillful means and plan of Buddhism, thus the sutra's former disavowal of all competitive doctrinal disputes. Crucially, not only are there multiple Buddhas in this view, but an infinite stream of Buddhas extending through unquantifiable eons of time ("thousands of kotis of kalpas") in a ceaseless cycle of creations and conflagrations. In the vision set out in this sutra, moreover, not only are Buddhas innumerable, but the universe encompasses realms of gods, devas, dragons and other mythological beings, requiring numerous dimensions to contain them. Buddhas are portrayed as the patient teachers of all such beings.